Perlmutter, Saul

Saul is an astrophysicist and professor at Lawrence Berkeley National Laboratory, where he heads the Supernova Cosmology Project. It was his group that found evidence that the expansion of the universe is accelerating, a discovery that suggests the existence of a previously unknown “dark energy” (comprising ~75% of the universe). This discovery is considered one of the most startling and disruptive in contemporary science and he has been awarded numerous prizes for it. As Saul put it: “As with most physicists, my research is primarily motivated by questions of what are universe is made of and how it works, and I have been approaching these questions using astrophysics measurements. Our work with supernovae, which was intended to measure the deceleration of the universe’s expansion due to gravity (in other words, we were “weighing the universe”), turned out to see an acceleration.  This unexpected result suggests that most of the universe may be primarily (~75%) made of a previously unknown energy -- now called “dark energy” -- that is accelerating the expansion. This dark energy is a new mystery, raising many new questions:  What is the physics behind it? Is it vacuum energy? Does it behave as Einstein’s cosmological constant or has it been evolving with redshift? I think we have an excellent chance to make progress on answering these fundamental questions in the next few years…. When we started the project we thought that whatever answer we found would be exciting: if the universe were decelerating enough then it would be finite and coming to an end; if not then the universe is likely infinite in space and time. We could not have imagined the actual outcome, a surprise that presents a major puzzle for fundamental physics. Since 1998 we and others have begun the exciting, painstaking effort to collect new data to explore this puzzle. We have even begun developing a new space telescope. Perhaps when my three-year-old daughter, Noa, enters high school, humankind will have the next answers -- or, better yet, new surprising questions about our world ”